The present invention relates generally to a braking system for a device having a self-propelled chassis. More particularly, the invention relates to a an automatic braking system for a medical diagnostic device in which an operator operates the controls while walking behind the device.
Various types of equipment are made mobile by mounting the equipment on a self-propelled chassis. Mobility is particularly significant for medical diagnostic equipment, such as an X-ray device and a scintillation camera device for obtaining diagnostic images of a patient. In many cases, the patient requires intensive care or critical care and cannot be moved, so the diagnostic device must be transported to the patient. The device may be required to be operated virtually anywhere in the hospital. The device must maneuver along extremely long corridors, around life support systems and around monitoring systems or traction devices. The device must also move in and out of elevators, through doorways, up wheelchair ramps, over carpeting and tile, and across small open thresholds.
A problem is presented by the mobilization of scintillation camera equipment which is used to detect gamma rays photons emitted from a body in which a radioisotope has been infused to produce a diagnostic image of the patient. Scintillations occur where photons are absorbed by crystalline material. The scintillations are received by a detector head which contains scintillation crystals, photomultiplier tubes and lead shielding. A typical system is based on the camera of Anger, as disclosed in U.S. Pat. No. 3,011,057, and is herein incorporated by reference. The detector head, along with the suspension arm, weighs approximately 300 pounds. The suspension system and column for the detector head add more weight along with the very high density of electronic instrumentation used to analyze and display the diagnostic images of the patient. The substantial size and weight of the diagnostic equipment requires a similarly substantial chassis and mobility drive system to transport the equipment. The combined equipment and mobility chassis weighs over 2,000 pounds and presents the problem of safely maneuvering, steering and braking the device while it is being moved and then stabilizing the device once it is in position.
Typical mobility chassis of the prior art use conventional four-wheeled systems with mechanical steering and braking systems. A particular problem with mobility devices is in the application of the braking systems. Typical devices of the prior art relied upon the natural friction of the system to stop the devices once power was reduced to the propelling system. A brake was either "on" or "off" and was utilized primarily as a parking brake or as an emergency brake in critical situations.
Accordingly, one object of the present invention is to provide a diagnostic device which can be safely operated at relatively high speeds through corridors and can be slowly maneuvered into tight locations.
Another object is to provide a diagnostic device which can be easily controlled by an operator walking behind the device.
Still a further object of the present invention is to provide a diagnostic device having a steering system which can be readily operated with either hand to control direction, velocity, steering and braking for the device.